Method and structure for thin film photovoltaic cell using similar material junction

Abstract

A method for forming a thin film photovoltaic device. The method provides a transparent substrate including a surface region. A first electrode layer overlies the surface region. A copper layer is formed overlying the first electrode layer and an indium layer is formed overlying the copper layer to form a multi-layered structure. At least the multi-layered structure is subjected to a thermal treatment process in an environment containing a sulfur bearing species to forming a bulk copper indium disulfide. The bulk copper indium disulfide material has a surface region characterized by a copper poor surface region having a copper to indium atomic ratio of less than about 0.95:1 and n-type impurity characteristics. The bulk copper indium disulfide material excluding the copper poor surface region forms an absorber region and the copper poor surface region forms at least a portion of a window region for the thin film photovoltaic device. The method optionally forms a high resistivity transparent material having an intrinsic semiconductor characteristic overlying the copper poor surface region. A second electrode layer overlies the high resistivity transparent layer.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS[0001]This application claims priority to U.S. Provisional Patent Application No. 61 / 116,625, filed Nov. 20, 2008, entitled “METHOD AND STRUCTURE FOR THIN FILM PHOTOVOLTAIC CELL USING SIMILAR MATERIAL JUNCTION” by inventor Howard W. H. Lee, commonly assigned and incorporated by reference herein for all purposes.BACKGROUND OF THE INVENTION[0002]The present invention relates generally to photovoltaic materials and manufacturing method. More particularly, the present invention provides a method and structure for manufacture of thin film photovoltaic cells. Merely by way of example, the present method and materials include absorber materials made of copper indium disulfide species, copper tin sulfide, iron disulfide, or others for single junction cells or multi junction cells.[0003]From the beginning of time, mankind has been challenged to find way of harnessing energy. Energy comes in the forms such as petrochemical, hydroelectric, nuclear, wind,...

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Benefits of technology

[0012]Merely by way of example, the present method and materials include absorber materials made of copper indium disulfide species, copper tin sulfide, iron disulfide, or others for single junction cells or multi junction cells.

Problems solved by technology

Unfortunately, the supply of petrochemical fuel is limited and essentially fixed based upon the amount available on the planet Earth.

Additionally, as more people use petroleum products in growing amounts, it is rapidly becoming a scarce resource, which will eventually become depleted over time.

Although solar energy is environmentally clean and has been successful to a point, many limitations remain to be resolved before it becomes widely used throughout the world.

However, crystalline materials are often costly and difficult to make on a large scale.

Additionally, devices made from such crystalline materials often have low energy conversion efficiencies.

Similar limitations exist with the use of thin film technology in making solar cells.

That is, efficiencies are often poor.

Additionally, film reliability is often poor and cannot be used for extensive periods of time in conventional environmental applications.

Often, thin films are difficult to mechanically integrate with each other.

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